Which atom(s) in the molecule CH3OCH3 (dimethyl ether) display tetrahedral electron-pair geometry?

• A. Both carbon atoms
• B. Both carbon atoms and the oxygen atom
• C. Only the oxygen atom
• D. Both carbon atoms and the oxygen atom

Answer: (B)

Verified step by step guidance

1. Identify the central atoms in the molecule CH3OCH3 (dimethyl ether). Here, the atoms of interest are the two carbon atoms and the oxygen atom connecting them.
2. Recall that electron-pair geometry depends on the number of regions of electron density (bonding and lone pairs) around an atom, not just the number of bonded atoms.
3. For each carbon atom in CH3OCH3, count the regions of electron density. Each carbon is bonded to three hydrogen atoms and one oxygen atom, totaling four regions of electron density, which corresponds to a tetrahedral electron-pair geometry.
4. For the oxygen atom, count the regions of electron density. Oxygen is bonded to two carbon atoms and has two lone pairs, making a total of four regions of electron density, which also corresponds to a tetrahedral electron-pair geometry.
5. Conclude that both carbon atoms and the oxygen atom in dimethyl ether have tetrahedral electron-pair geometry because each has four regions of electron density around it.